The use of contact lenses to correct vision is common place in today's world. There are presently several traditional methods of high-volume low-cost contact lens manufacture. These methods include, but are not limited, to cast molding, spin casting, lathing, and using a technique known in the industry as “Lightstream Technology”, and any combinations thereof.
More recently, a new system and method for manufacturing contact lenses has been disclosed in which an infinite number of truly custom lenses can readily be produced in a cost effective manner. U.S. Pat. No. 8,317,505, which is incorporated herein by reference in its entirety, discloses a method for growing a Lens Precursor Form on a single male optical mandrel on a voxel by voxel basis by selectively projecting actinic radiation through the optic mandrel and into a vat or bath of liquid polymer. The optical mandrel and Lens Precursor Form are then removed from the vat and inverted so that the convex surface of the optic mandrel is upright. Following a dwell period during which uncured residual liquid monomer from the bath that remains on the Lens Precursor Form flows under gravity over the Lens Precursor Form, such liquid is then cured to form the final lens. As described therein, a truly custom lens can be produced for any given eye.
To maximize the benefit to a patient of a truly custom lens manufactured as set forth in U.S. Pat. No. 8,317,505 or otherwise, requires precision in both measuring a patient's corrective needs to design the custom lens, and also in assessing the actual fit of the lens on the patient's eye and adjusting the design accordingly to account for Lens Position Error. With regard to the latter, it is well known that the physiology of the patient's eye itself, of the patient's eyelid, and the interaction between the two can affect the actual positioning of the lens upon the eye. Often these factors result in a lens orienting itself upon the eye in a less than optimal manner, such as laterally offset from the intended position or at an angular orientation relative to what was intended. This results in less than optimal vision through that lens since the optic zone of the lens is not oriented appropriately over the patient's eye. If the precise fit of the lens on the patient's eye can be assessed accurately, then the custom lens can be redesigned to account for Lens Position Error, such as by moving the optic zone accordingly, yielding a truly custom lens that better corrects the patient's vision in the real setting as opposed to a hypothetical design setting.
In assessing a patient's vision, it is still commonplace for eye care practitioners to utilize a simplistic, well-known slit lamp. Known prior art has leveraged markings on a fitting lens to assist practitioners in assessing the actual fit of a contact lens on a patient's eye when using a slit lamp or otherwise additional manufacturing step to place them there, such as milling, scribing or stamping. Other methods of placing these types of markings on a lens include ink jet printing, pad printing or the like. Another method is to subsequently add or remove material from the lens such as is These markings are placed on the front or back curve of the lens, and require an disclosed in U.S. Pat. No. 8,636,357. The cost and complexity or these additional manufacturing steps increases the cost of any lens having such fiducial markings.
The present invention provides a lens having edge features that are designed to be visible to a practitioner and enable fitting assessment using a traditional slit lamp, or any other type of more sophisticated device, and require no further steps in the manufacturing process. The edge features disclosed herein are further advantageous in that they are visible to the bare eye when in hand and enable a patient to readily verify the correct orientation of the lens before placing it on the eye, such as by visualizing whether the lens is upside down or right-side up, or whether the lens has inverted or turned inside-out. Further, the lens edge features described herein are preferably positioned outside of the optic zone and as such are not readily visible to the patient or any other casual observer when placed on the eye, rendering them suitable for normal, everyday use by a patient, thereby eliminating the need for specialized trial lenses.